The present invention generally relates to a magnetic head for a magnetic recording apparatus. More particularly, the invention concerns a magnetic head which is advantageously suited for use in a magnetic recording apparatus designed for high density magnetic recording such as a VTR and a magnetic disk apparatus in which a high coercive force magnetic recording medium is employed, a magnetic disk apparatus in which a perpendicular magnetic recording method is adopted and the like.
A ferromagnetic amorphous alloy film promises a useful magnetic material in view of the fact that it has excellent characteristics as a soft magnetic material such as high permeability characteristics over a wide range of compositions and high saturation flux density beyond 10 KG.
Japanese Patent Unexamined Publication No. 155,513/83 discloses, a magnetic head in which each of core blocks constituting parts of the head has an end face inclined toward a magnetic gap interposed between the core blocks, wherein a ferromagnetic amorphous alloy film exhibiting a high saturation flux density is deposited on each of the inclined end faces of the core blocks.
More specifically, these heads are mainly composed of a first core block, a second core block and an excitation coil wound on the first core block. Each of the first and second core blocks is formed of ferrite or the like material and includes a protective core portion having a ridge of a mountain-like shape located substantially at a center of the end face of the core block facing in opposition to the magnetic gap, and a ferromagnetic amorphous alloy film deposited on the end face of the protective core portion and exhibiting a high saturation flux density.
The first core block, the ridge thereof and the ferromagnetic amorphous alloy film on one hand and the second core block, the ridge thereof and the ferromagnetic amorphous alloy film deposited thereon on the other hand have respective shapes symmetrical relative to the interposed magnetic gap and are bonded together by a bonding agent such as a glass material.
The magnetic head according to the prior proposal is designed for the use primarily in a VTR, floppy-disc drive and the like in which the track width is in a range of ca. 10 .mu.m. The thickness of the ferromagnetic amorphous alloy film employed in the magnetic head under consideration is about 5 m to 150 .mu.m. The ferromagnetic amorphous alloy film of the thickness on the order mentioned above suffers remarkable dispersion in the magnetic anisotropy, involving reduction in the permeability. In other words, the magnetic characteristics inherent to the ferromagnetic amorphous alloy forming the film are not fully made use of. As a consequence, recording and reproducing characteristics may not be satisfactory for the magnetic head.
Similar heads are disclosed in U.S. Pat. Nos. 4,559,572 and 608,407.
Conventionally, in order to enhance the recording and reproducing characteristics of the head, the ferromagnetic amorphous alloy film for the head core material is implemented in a laminated multi-layer structure in which ferromagnetic metal layers are laminated with interposition of insulation layers of SiO.sub.2, Al.sub.2 O.sub.3 or the like in an effort to ensure a high permeability even in a high frequency band.
When the multi-layered ferromagnetic amorphous alloy film including the interposed insulation layers referred to as spacer layers is applied to a magnetic head, the effects as obtained are very significant. In reality, excellent recording/reproducing characteristics can be realized over a wide frequency range inclusive of a high frequency band. It is however noted that when the insulation layer is employed as the spacer layer in implementing the multi-layer structure of the ferromagnetic amorphous alloy film, there may arise such a case in which the spacer layer functions as a pseudo-magnetic gap, imposing restriction to the design of structure of the magnetic head as well as the multi-layer film and thus making it difficult to realize the magnetic head on optimum conditions.